As semiconductor elements are increasingly developed to achieve higher integration, higher power and higher speed, they generate significant heat (or are significantly heated) in operation. Accordingly, the semiconductor element is mounted on a heat radiating member (referred to as a heat sink, a heat spreader, etc.) to dissipate the semiconductor element's heat externally via the heat radiating member.
The heat radiating member is required to have high thermal conductivity and in addition a small difference in coefficient of thermal expansion from the semiconductor element. Accordingly, as the heat radiating member, a composite material is utilized in which particles of a satisfactorily thermally conductive material such as diamond and SiC are dispersed in a metal matrix such as Ag, Cu and Al and thus composited therewith. For example, as a composite material of diamond, Ag/diamond, Cu/diamond, Al/diamond, etc. are known, and as a composite material of SiC, Al/SiC etc. are known.
The above composite material is produced for example as follows: a powder of the satisfactorily thermally conductive material is introduced into a container or a die and subsequently thereon a powder, plate or the like of a metal that will serve as a metal matrix is disposed, and in that condition they are heated and the metal is thus molten and infiltrated between the particles of the satisfactorily thermally conductive material to produce the composite material. Patent documents 1-3 disclose a technique in which in a metal/diamond composite material an element of group 4 of the periodic table such as Ti is added to form a carbide of the element of group 4 of the periodic table on a surface of diamond particles to improve the diamond particle in wettability to enhance adhesion and bindability between the metal matrix and the diamond particle.